Establishment and Validation of a UPLC-MS/MS Bioassay for the Quantification of Infigratinib in Rat Plasma

Infigratinib (INF) is a fibroblast growth factor receptor (FGFR)-specific tyrosine kinase inhibitor for the therapy of advanced cholangiocarcinoma. However, CYP3A4 polymorphisms and CYP3A4 inducers or inhibitors might affect the pharmacokinetics of INF. Clinical evaluation of drug-drug interactions and adverse effects in these patients was necessary with reference to INF levels in vivo. The presently conducted study optimized a reproducible and rapid ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analytic technique, which was validated and applied to determine INF concentrations in Sprague-Dawley (SD) rat plasma and pharmacokinetic studies. Protein was precipitated by adding acetonitrile to plasma samples, followed by gradient elution on a Waters Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) for complete chromatographic separation of the analyte and derazantinib (used as internal standard, IS). A gradient elution of 0.1% formic acid aqueous solution and acetonitrile at a flow rate of 0.30 mL/min was applied as the mobile phase for this analysis. The ion transitions of INF and IS were m/z 599.88 → 313.10 and m/z 468.96 → 382.00 during UPLC-MS/MS detection, respectively, by multiple reaction monitoring (MRM). The methodological validation demonstrated that INF presented high linearity over the concentration of 2–600 ng/mL. The lower limit of quantification (LLOQ) for this experiment was 2 ng/mL, of which the precisions and accuracies were within the permissible levels. Inter-day and intra-day precisions were demonstrated to be within reasonable limits, which were within 15%, and the accuracies were determined to be between 2.2% and 11.4%. Moreover, the values of recovery, stability and matrix effect of INF were within the limits of acceptability. The pharmacokinetics of INF in SD rats was investigated by gavage administration of 10 mg/kg INF, followed by the application of the developed UPLC-MS/MS analytical method to detect the content in plasma and derive the main pharmacokinetic parameters.